Safety remote control for a carrier



United States Patent 3,351,945 SAFETY REMOTE CONTROL FOR A CARRIERVincent S. Borsattino, Chursel E. Marker, and Jesse W.

Shalla, Gary, Ind., assignors to United States Steel Corporation, acorporation of Delaware Filed Feb. 7, 1964, Ser. No. 343,411 3 Claims.(Cl. 343-225) ABSTRACT OF THE DISCLOSURE A safety remote control for acarrier wherein the transmitter transmits two signals of substantiallydifferent frequency and the receiver for the safety signal includes afirst tuned circuit tuned to the safety signal frequency and a secondtuned circuit tuned to and inductively coupled to the first tunedcircuit.

This invention relates to a safety remote control for a carrier and moreparticularly to a control for directing the movements of overhead cranesand locomotives from a remote position. A similar control system isshown in our co-pending application Ser. No. 337,037 filed Jan. 10,1964. The control system of the present application is particularlydirected to safety features. While our co-pending application has safetyfeatures which will prevent accidental operation of the control undermost all conditions, the carrier signal is applied in such a manner thatthe manual magnetic disconnect is energized and crane move mentaccomplished by modulating the carrier signal. In some instances randomnoises might possibly cause movement of the carrier. The random noisemight be an arc welder or other equipment found in a steel mill althoughin several months operation of the control of our co-pending applicationthere has been no operation of the crane due to random noises. Thesafety control of the co-pending application also requires asuperhetrodyne safety receiver which is relatively expensive.

It is therefore an object of our invention to provide a carrier controlsystem which eliminates the need of a superhetrodyne safety receiver.

Another object is to provide such a control which cannot be actuated byrandom noises.

These and other objects will be more apparent after referring to thefollowing specification and attached drawings, in which:

FIGURE 1 is a schematic view of a transmitter used with our invention;

FIGURE 2 is a schematic view of a crane with certain control parts showntherein; and

FIGURE 3 is a schematic view of the receiver of our invention and themotor controls associated therewith.

Referring more particularly to FIGURE 1 of the drawings, referencenumeral 2 indicates a battery or other low voltage source. Power fromthe battery 2 is delivered to variable frequency multi-vibrators 4A, 4B,4Cand 4D. Output switches'6A, 6B, 6C and 6D are provided for themulti-vibrators 4A, 4B, 4C and 4D. The outputs of the multi-vibratorsare selectively connected to an audio amplifier 8 and the output ofaudio amplifier 8 is applied to an audio frequency amplifier 10 havingan antenna 12 associated therewith. The output of an oscillator 14 is applied to the audio frequency amplifier 10. Also connected to the battery2 is a safety channel transmitter 16 having an antenna 18. Flow of powerfrom the battery 2 to the various parts is controlled by means of aswitch 19. The transmitter shown diagrammatically in FIGURE 1 anddescribed above is the same as in our above identified co-pendingapplication. However, any suitable transmitter may be use.

While the invention may be used to operate any type of ice mobileequipment it will be described with reference to an overhead cranecarried on rails 20. The crane includes a bridge 22 which moves alongthe rails 20, a trolley 24 which moves transversely of the bridge and ahoist 26 mounted on thetrolley 24. The bridge 22 is moved by means of amotor 28 having a control panel 30 for determining the direction andspeed of its movement. The trolley 24 is moved across the bridge 22 bymeans of a motor 32 whose speed and direction of movement are determinedby means of a control panel 34. The hoist 26 is raised and lowered bymeans of a motor 36, the speed and direction of movement of which iscontrolled by means of a control panel 38. The control panels 30, 34 and38 contain the usual control relays which are used to energize theirrespective motors for movement in forward and reverse directions atvarious speeds. The parts of the crane so far described areconventional. A superheterodyne receiver 40 having an antenna 40T ismounted on the bridge 22.

FIGURE 3 shows diagrammatically the receivers and control circuits. Theoutput of the superhetrodyne 40 is impressed on a detector 42 which inturn has its output connected to a limiter 44. The limiter 44 includesa. capacitor 45 connected to base 46B of transistor 46 and also througha capacitor 50 and resistor 52 connected in series to the negativeterminal of a power source 54. Emitter 46B is connected through resistor56 to emitter 58E of transistor 58. Collector 58C is connected to thenegative terminal of power source 54 through a resistor 60 and to theprimary 62F of transformer 62. A shaper 64 includes secondary 62S oftransformer 62 which is connected through a choke 66 to primary 68P oftransformer 68.

The ouput shaper 64 is connected to discriminators 70A, 70B, 70C and70D. The discriminators 70A, 70B and 70C are identical except for valuesof components and their outputs are connected to servo-amplifiers 72A,72B, 72C,respectively. The servo-amplifiers 72A, 72B and 72C operatesegmented rotary switches 74A, 74B and 74C, respectively, which in turnare connected to control the operation of intermediate panels 76A, 76Band 76C,

respectively. The intermediate panels 76A, 76B and 760 are connected tocontrol panels 30, 34 and 38, respectively. The intermediate panels 76A,76B and 76C contain relays having contacts capable of handling the heavycurrents needed to operate the relays of the control panels. Power forthe intermediate panels and control panels are provided from controlpower lines L1, L2. The parts of FIGURE 3 so far described are the sameas in our above identified co-pending application.

According to the present invention a resistor 78 is connected to thenegative terminal of power source 54 in series with resistor 60 and asilicon controlled rectifier 80 is connected between the resistors 60and 78 and also tothe negative terminal of power source 54. Therectifier 80 is also connected in series with a current sensitive relaycoil 82 and relay contact 84C to the positive terminal of power source54. Relay coil 82 has a normally open contact 82C which is connected inline L1 leading to control panels 30, 34 and 38. Contact 84C iscontrolled by a voltage sensitive relay coil 84 which also operatescontact 84C1. Contacts 84C and 84C1 are both normally open. Contact 84C1is connected to the positive terminal of power source 54 in series witha current sensitive'relay coil 86 which has a normally open contact 86Cin power line L1 leading to intermediate panels 76A, 76B and 76C.-

nected in parallel with resistors 90 and 92. Base 94B is connected to aresistor 98. Resistor 100 is connected in parallel with resistors 90 and92 and resistor 102 is connected in parallel with resistor 96. Acapacitor 104 is connected in parallel with resistor 102. A dioderectifier 106 is connected in series with a variable capacitor 108across capacitor 104. An inductor 110 is connected in parallel withvariable capacitor 108. A safety channel receiving antenna 112 isconnected in series with variable capacitors 114 and 116 to ground.Inductor 118 is connected in parallel with capacitor 116. Capacitor 108and inductor 110 constitute one tuned circuit 120 and capacitor 116 andinductor 118 constitute another tuned circuit 122. Both circuits aretuned to the same resonant frequency but are individually adjustable.

In operation, when the operator wishes to warn other workmen of themovement of the crane he closes switches 6D and 19 so that themultivibrator 4D oscillates and applies a signal to the audio amplifier8 which amplifies the signal and applies it to the RF amplifier 10. Thissignal is modulated on the carrier freqency which is generated in theoscillator 14 and is transmitted through the air waves by means ofantenna 12. This signal is picked up by antenna 40T and is fed into thereceiver 40 where this incoming signal is mixed with a signal from theoscillator forming part of the receiver 40. The output of the receiver40 is detected by detector 42 and is then amplified and limited by thelimiter 44. The limiter 44 transmits the audio portion of the waveshaped signal to the sharper 64 where it is turned into a sine wavewhich is impressed on discriminators 70A, 70B, 70C and 70D. Nothingoccurs in discriminators 70A, 70B and 700 because they are not tuned tothe frequency of multi-vibrator 4D. However, discriminator 70D is tunedto the frequency of the multivibrator 40 so that the bell, not shown, iscaused to ring in the same manner as in our above entitled co-pendingapplication.

Assuming that it is desired to move the bridge 22 forwardly, theoperator moves switch 6A to the broken line position shown in FIGURE 1and at the same time adjusts the frequency of the multi-vibrator 4A inthe desired direction to move the bridge motor 28 at the desired speedin the desired direction. Switch 19 is also closed at this time. Theoutput signal of multi-vibrator 4A will be sent through in the samemanner as that of multi-vibrator 4D previously described. However, thefrequency of this signal will be different than that of multi-vibrator4D and will' be the same frequency as discriminator 70A. As transistor58 goes into conduction there is a voltage drop across resistor 60 andalso across resistor 78. Resistors 60 and 78 form the collector load fortransistor 58 and also make up a voltage divider network for the siliconcontrolled rectifier 80. As the voltage drops across resistor 78,current flows and causes silicon controlled rectifier 80 to go intoconduction. When silicon controlled rectifier 80 is conducting andcontact 84C is closed, relay coil 82' will be energized to close contact82C, this applying power to the control panel 30 which will in turnallow movement to occur provided contact 86C is closed. At the same timea signal from safety channel transmitter 16 is picked up by antenna 112and coupled through the variable capacitor 114 into tuned circuit 122.The signal developed in tuned circuit 122 is then inductively coupledinto tuned circuit 120. The positive portion of the signal is thenpassed through the rectifier 106 and biasing resistor 98 onto the baseelectrode 94B of transistor 94. Condenser 104 connected inparallel withresistor 102 acts as a filter and biasing network for transistor 94.Resistor 96 acts as a current limiting resistor. Resistor 100 acts aspart of the voltage dividing network for biasing base electrode 94B oftransistor 94. Resistors 90 and 92 form the collector load of transistor94 and also form a voltage divider network for the silicon controlledrectifier 88. As the incoming signal develops a voltage across resistors90 and 92, transistor 94 conducts and causesrelay 84 to close itscontacts 84C and 8401. Closing of contact 84C energizes relay coil 82and closing contact 84C1 energizes relay coil 86. As a voltage isdeveloped across resistor there is suflficient current to triggersilicon controlled rectifier 88 which will close relay contact 86C. Theclosing of contacts 82C and 86C will apply power to the intermediatepanels 76A, 76B and 76C and to control panels 30, 34 and 38. Thus thesignal which is picked up by discriminator 70A will be delivered toservo-amplifier 72A so that the motor 28 will rotate to cause the bridgeto move at the desired speed in the desired direction. When the cranereaches its desired position the operator moves switch 6A to the solidline position shown and the movement of the crane will cease. If thetrolley 24 is not in the desired position the operator will move switch6B to its broken line position and adjust the frequency of multivibrator4B to the position where operation of motor 32 will be that desired. Thefrequency of the generated signal will be only within the frequencyresponse of discriminator 708 so that the output of discriminator 7 0Bwill be impressed on the servoamplifier 72B and switch 74B will controlmovement of the motor 32 to move the trolley in the desired direction.When the trolley 24 reaches its desired position the switch 6B will bemoved to its solid line position and movement of the trolley will cease.The hoist 26 is then lowered by the operator moving the switch 60 to thebroken line position and adjusting the frequency of the multi-vibrator4C as desired. The signal will then be transmitted in the same manner asthat described above and picked up by discriminator 70C and the outputof discriminator 70C will be impressed on servo-amplifier 720 whichthrough the switch 740 will cause operation of motor 36 to lower thehoist. When the hoist 26 reaches the desired position the operator movesswitch 6C to the solid line position stopping the movement of the hoist.He then attaches the article to be lifted to the hoist and assuming thatthe crane is to be returned to its original position the above described operations are repeated in reverse order. The only difference isthat the multi-vibrators 4A, 4B and 4C are adjusted to a differentfrequency. It will be seen that except for the safety receiver and theoperation of the as sociated safety devices the operation of the controlis the same as in our above identified application. Also the improvementof the present application can be used when a single control signal isutilized.

While one embodiment of our invention has been shown and described itwill be understood that other adaptations and modifications may be madewithout departing from the scope of the following claims.

We claim:

1. A control for a carrier comprising a first transmitter fortransmitting a first signal of known frequency, a second transmitter fortransmitting a second signal having a frequency substantially differentthan that of the first transmitter, said transmitters being at aposition remote from said carrier, a first receiver mounted on saidcarrier for receiving the signal transmitted by said first transmitter,a detector connected to the output of said first receiver, a limiterconnected to the output of said detector, said limiter including a firsttransistor connected to receive the output of said detector,discriminator means connected to the output of said limiter fordetecting and distinguishing the frequency of said first signal, anelectrical powered device, second means operable by the output of saiddiscriminator means for operating said device, a silicon controlledrectifier connected in circuit with said transistor and switched on bysaid transistor, a power source, a first relay coil connected in serieswith said silicon controlled rectifier to said power source to allowcurrent to pass through said relay coil when the silicon controlledrectifier is turned on, a first tuned circuit tuned to the second signalfrequency for picking up a signal from said second transmitter, a secondtuned circuit tuned to the frequency of said first tuned circuit andinductively coupled thereto, rectifier means connected to the output ofsaid second tune-d circuit for passing one portion of the output signal,a second transistor, a second relay coil connected in series with saidsecond transistor to said power source, means connecting the output ofsaid rectifier means to said second transistor to switch the transistoron and allow current to pass from said power source to said second relaycoil, power supply means for said devices, and a normally open contactassociated with each of said relay coils, said relay coils closing saidcontacts when they are energized to permit flow of electricity from saidpower supply means to said electrical powered device when said secondmeans is operable.

2. A control for a carrier comprising a first transmitter fortransmitting a first signal of known frequency, a second transmitter fortransmitting a second signal having a frequency substantially differentthan that of the first transmitter, said transmitters being at aposition remote from said carrier, a first receiver mounted on saidcarrier for receiving the signal transmitted by said first transmitter,a detector connected to the output of said first receiver, a limiterconnected to the output of said detector, said limiter including a firsttransistor connected to receive the output of said detector,discriminator means connected to the output of said limiter fordetecting and distinguishing the frequency of said first signal, anelectrical powered device, second means operable by the output of saiddiscriminator means for operating said device, a silicon controlledrectifier connected in parallel with said first transistor between thetransistor collector and emitter and switched on by said transistor, apower source, a first current sensitive relay coil and a first normallyopen relay contact connected in series with the anode of said siliconcontrolled rectifier to said power source to allow current to passthrough said first current sensitive relay coil when the first normallyopen relay contact is closed and the silicon controlled rectifier isturned on, a first tuned circuit tuned to the second signal frequencyfor picking up a signal from said second transmitter, a second tunedcircuit tuned to the frequency of said first tuned circuit andinductively coupled thereto, a diode rectifier connected to the outputof said second tuned circuit, a second transistor connected in serieswith said diode rectifier to switch on said second transistor, a voltagesensitive relay coil connected in series with said second transistor tosaid power source, said voltage sensitive relay coil operating saidfirst normally open contact, a second normally open contact operable bysaid voltage sensitive relay coil, a voltage dividing network connectedin series with said second transistor, a second silicon controlledrectifier, a second current sensitive relay coil connected in serieswith said second normally open contact to said power source, anelectrical connection from said voltage dividing network to said secondsilicon controlled rectifier to allow said second transistor to switchon said second silicon controlled rectifier, power supply means for saiddevices, and a normally open contact associated with each of saidcurrent sensitive relay coils, said current sensitive relay coilsclosing said contacts when they are energized to permit fiow ofelectricity from said power supply means to said electrical powereddevice when said second means is operable.

3. A control for a carrier comprising a first transmitter fortransmitting a first signal of known frequency,

a second transmitter for transmitting a second signal hav ing afrequency substantially dilferent than that of the first transmitter,said transmitters being at a position remote from said carrier, at firstreceiver mounted on said carrier for receiving the signal transmitted bysaid first transmitter, a detector connected to the output of said firstreceiver, a limiter connected to the output of said detector, saidlimiter including a first transistor connected to receive the output ofsaid detector, discriminator means connected to the output of saidlimiter for detecting and distinguishing the frequency of said firstsignal, an electric motor, means operable by the output of saiddiscriminator means for controlling operation of said motor, powersupply means for said motor, a circuit connecting said power supplymeans to said motor, a first silicon controlled rectifier connected inparallel with said first transistor between the transistor collector andemitter and switched on by said transistor, a power source, a firstcurrent sensitive relay coil and a first normally open relay contactconnected in series with the anode of said first silicon controlledrectifier to said power source to allow current to pass through saidfirst current sensitive relay coil when the first normally open relaycontact is closed and the silicon controlled rectifier is turned on, afirst tuned circuit for picking up a signal from said secondtransmitter, a second tuned circuit tuned to the frequency of said firsttuned circuit and inductively coupled thereto, a diode rectifierconnected to the output of said second tuned circuit, a secondtransistor connected in series with said diode rectifier to switch onsaid second transistor, a voltage sensitive relay coil connected inseries with said second transistor to said power source, said voltagesensitive relay coil operating said first normally open contact, asecond normally open contact operable by said voltage sensitive relaycoil, a voltage dividing network connected in series with said secondtransistor, a second silicon controlled rectifier, a second currentsensitive relay coil connected in series with said second normally opencontact to said power source, and an electrical connection from saidvoltage dividing network to said second silicon controlled rectifier toallow said second transistor to switch on said second silicon controlledrectifier, each of said current sensitive relay coils having a normallyopen contact in said motor circuit, which contacts when closedpermitting operation of said motor when said second means is operable.

References Cited UNITED STATES PATENTS 3,090,959 5/ 1963 Marmont 343-2253,103,558 9/1963 Ligotky 340-171 3,103,611 9/1963 Hooper 343-2253,127,563 3/1964 Paulson 340-171 3,278,760 10/1966 Wagner 307-8853,278,821 10/ 1966 Gutzwiller 307-885 OTHER REFERENCES F Oliver and W.Ehrsam-z The Gate Controlled Switch, Motorola Monitor, vol. 2, January1964, pp. 24-28.

NEIL C. READ, Primary Examiner.

A. J. KASPER, Assistant Examiner.

1. A CONTROL FOR A CARRIER COMPRISING A FIRST TRANSMITTER FORTRANSMITTING A FIRST SIGNAL OF KNOWN FREQUENCY, A SECOND TRANSMITTER FORTRANSMITTING A SECOND SIGNAL HAVING A FREQUENCY SUBSTANTIALLY DIFFERENTTHAN THAT OF THE FIRST TRANSMITTER, SAID TRANSMITTERS BEING AT APOSITION REMOTE FROM SAID CARRIER, A FIRST RECEIVER MOUNTED ON SAIDCARRIER FOR RECEIVING THE SIGNAL TRANSMITTED BY SAID FIRST TRANSMITTER,A DETECTOR CONNECTED TO THE OUTPUT OF SAID FIRST RECEIVER, A LIMITERCONNECTED TO OUTPUT OF SAID DETECTOR, SAID LIMITER INCLUDING A FIRSTTRANSISTOR CONNECTED TO RECEIVE THE OUTPUT OF SAID DETECTOR,DISCRIMINATOR MEANS CONNECTED TO THE OUTPUT OF SAID LIMITER FORDETECTING AND DISTINGUISHING THE FREQUENCY OF SAID FIRST SIGNAL, ANELECTRICAL POWERED DEVICE, SECOND MEANS OPERABLE BY THE OUTPUT OF SAIDDISCRIMINATOR MEANS FOR OPERATING SAID DEVICE, A SILICON CONTROLLEDRECTIFIER CONNECTED IN CIRCUIT WITH SAID TRANSISTOR AND SWITCHED ON BYSAID TRANSISTOR, A POWER SOURCE, A FIRST RELAY COIL CONNECTED INSERIESWITH SAID SILICON CONTROLLED RECTIFIER TO SAID POWER SOURCE TO ALLOWCURENT TO PASS THROUGH SAID RELAY COIL WHEN THE SILICON CONTROLLEDRECTIFIER IS TURNED ON, A FIRST TUNED CIRCUIT TUNED TO THE SECOND SIGNALFREQUENCY FOR PICKING UP A SIGNAL FROM SAID SECOND TRANSMITTER, A SECONDTUNED CIRCUIT AND TUNED TO THE FREQUENCY OF SAID FIRST TUNED CIRCUIT ANDINDUCTIVELY COUPLED THERETO, RECTIFIER MEANS CONNECTED TO THE OUTPUT OFSAID SECOND TUNED CIRCUIT FOR PASSING ONE PORTION OF THE OUTPUT SIGNAL,A SECOND TRANSISTOR, A SECOND RELAY COIL CONNECTED IN SERIES WITH SAIDSECOND TRANSISTOR TO SAID POWER SOURCE, MEANS CONNECTING THE OUTPUT OFSAID RECTIFIER MEANS TO SAID SECOND TRANSISTOR TO SWITCH THE TRANSISTORON AND ALLOW CURRENT TO PASS FROM SAID POWER SOURCE TO SAID SECOND RELAYCOIL, POWER SUPPLY MEANS FOR SAID DEVICES, A NORMALLY OPEN CONTACTASSOCIATED WITH EACH OF SAID RELAY COILS, SAID RELAY COIL CLOSING SAIDCONTACTS WHEN THEY ARE ENERGIZED TO PERMIT FLOW OF ELECTRICITY FROM SAIDPOWER SUPPLY MEANS TO SAID ELECTRICAL POWER DEVICE WHEN SAID SECONDMEANS TO OPERABLE.